Conventionally, for instance, a general solenoid valve is composed as shown in FIG. 14.
That is, as shown in FIG. 14, a solenoid valve 200 is provided with a control unit 204 comprising a valve element 202.
Moreover, the control unit 204 of this solenoid valve 200 is provided with an electromagnetic coil 208 through which a driving portion 206 is passed as shown in FIG. 14.
In addition, the electromagnetic coil 208 is provided with a bobbin 220 where the winding wire is rolled, and as to surround the periphery of the bobbin 220, it is molded with a molding resin 212. In addition, as shown in FIG. 14, the electromagnetic coil 208 is provided in a magnetic frame 214, and fixed to the driving portion 206 by the magnetic frame 214.
That is, the driving portion 206 is inserted in a driving portion inserting through hole 218 formed at the center section of a base plate portion 216 of the magnetic frame 214 and a driving portion inserting through hole 222 of the bobbin 220. In addition, into a bolt inserting through hole 226 formed at the upper part of an attracting member 224 of the driving portion 206, a fastening bolt 232 is screwed together, through a bolt inserting through hole 230 formed at the center section of an upper plate portion 228 of the magnetic frame 214.
As a result, an electromagnetic coil 208 is inserted in the driving portion 206 and is fixed, so that a control unit 204 of the solenoid valve 200 is composed.
In addition, the driving portion 206 is provided with a plunger casing 234, and a plunger 236 in which the valve element 202 is fixed that can be moved upwardly and downwardly in this plunger casing 234. In addition, between the attracting member 224 and the plunger 236, the plunger 236 is urged downwardly, that is, an urging spring 240 that urges the valve element 202 in the direction of the valve seat 238 is disposed.
As for such solenoid valve 200, by applying an electric current to the electromagnetic coil 208, the plunger 236 is moved in the directions of the attracting member 224 against the urging spring 240. As a result, the valve element 202 connected with the plunger 236 is separated from the valve seat 238, so that a valve port 242 is opened.
Moreover, by interrupting the application of the electric current to the electromagnetic coil 208, the plunger 236 is moved in the direction that separates from the attracting member 224 by the urging force of the urging spring 240. As a result, the valve element 202 connected with the plunger 236 abuts a valve seat 238, and the valve port 242 is closed.
Moreover, when the alternating current is applied to the electromagnetic coil 208, the magnetic flux is generated. Consequently, the plunger 236 is moved in the direction of the attracting member 224 against the urging spring 240. As a result, the state that the plunger 236 and the attracting member 224 abut each other, that is, the state that the valve element 202 is separated from the valve seat 238 and the valve port 242 is opened is maintained.
Conventionally, for the generation of the eddy current, in an annular groove 246 for the coil installation which is formed to a lower end surface 244 that faces to the plunger 236 of the attracting member 224, an annular shading off coil 248 (shading off ring) is installed.
In this case, the electromagnetic coil 208 which is used to drive the solenoid valve 200, power consumption is different in each power-supply voltage. Therefore, it is necessary to prepare it by the winding specification that does not exceed the temperature rise tolerance limit of electromagnetic coil 208.
Moreover, in the conventional solenoid valve 200, after the plunger 236 is attracted in the direction of the attracting member 224, it is necessary to keep the application of the electric current to electromagnetic coil 208. As a result, it is a fact to consume useless power.
By the way, in Patent Document 1 (JP 3777265, B), in order to attach the plunger which is integral to the valve element to a core and to hold attachment, a solenoid valve that controls electric current thrown to a coil is proposed. In this solenoid valve, the attraction is improved when the plunger is attached, and the electric current thrown to hold attachment is made a low current and unnecessary electricity consumption is reduced.
For that purpose, the solenoid valve drive control device 300 of this Patent Document 1, comprising, as shown in the block diagram of FIG. 15, a full-wave rectifier circuit portion 302 that converts the ac power supply into the dc power supply, and a power supply smooth portion 304 that takes out the voltage more than the definite value from the power-supply voltage which is made direct current by the full-wave rectifier circuit portion 302 and smoothes it. Moreover, a comparison operation portion 308 that controls the application of the electric current and the interruption of the application of the electric current to a solenoid (electromagnetic coil) 306, and a driver element portion 310 to which the application of the electric current and interruption of the application of the electric current to the electromagnetic coil 306 are operated by outputting of a comparison operation portion 308.
In addition, it comprises, in order to flow the electric current about twice as a minimum holding current necessary to make the core (attracting member) attach the plunger by them into electromagnetic coil 306, and an attaching electric current indication portion 312 that indicates the electric current application time to the comparison operation portion 308. Moreover, in order to flow the electric current necessary for holding attachment of the plunger and the core to the electromagnetic coil 306, an attachment holding current indication portion 314, in which instruction of time of the application of the electric current and interruption of the application of the electric current to the electromagnetic coil 306 is indicated to the comparison operation portion 308.
That is, by the dc power supply by the full-wave rectifier circuit portion 302, an electric current, which is necessary to make the plunger to be attached to the core, is flowed in the electromagnetic coil 306. As a result, the plunger is attached to the excited core.
In addition, the application of the electric current and interruption of the application of the electric current to the electromagnetic coil 306 by a driver element portion 310 are controlled on the basis of the output from the comparison operation portion 308. As a result, holding attachment is performed by the electric current about twice as a minimum holding current necessary for being flowed when attachment is held.
In that case, the electric current application time, for which the electric current necessary for the first attachment is flowed to the electromagnetic coil 306, is decided by the attaching electric current indication portion 312. Moreover, the and the time of application of the electric current and interruption of the application of the electric current, for which the electric current necessary for holding attachment after it is attached are applied and interrupted, is decided by the attachment holding current instruction portion 314.
As a result, the electric current applied to the electromagnetic coil 306 can be increased to the maximum. Consequently, when the plunger is attached and is held to the core, the electric current that flows to the electromagnetic coil 306 becomes a low current and unnecessary electricity consumption can be reduced.
However, in the solenoid valve drive control device 300 of Patent Document 1, as shown in the drawing, the shading off coil (shading off ring) is installed in the core (attracting member). Therefore, power-factor worsens by inserting the shading off coil. As a result, moreover, the predetermined attraction is not obtained by the temperature rise of the electromagnetic coil by the application of the electric current. Consequently, the winding wire of the electromagnetic coil should be extra rolled, and it becomes a factor that the cost increases.
Moreover, in the solenoid valve drive control device 300 of Patent Document 1, after the plunger is attracted in the direction of the attracting member, a minimum holding current should keep being applied to the electromagnetic coil. As a result, useless power is consumed.
On the other hand, in Patent Document 2 (JP4911847, B), the air conditioning machine comprising the solenoid valve controller is disclosed.
That is, the solenoid valve controller 400 of Patent Document 2 comprises, as shown in the block diagram of FIG. 16, a positive characteristic temperature coefficient element 404, which is connected with a valve coil 402 of the four-way switching solenoid valve, and a relay 406 as the first switching device, which is connected with the positive characteristic temperature coefficient element 404.
Moreover, a diode D1 in which the cathode is connected with the valve coil 402, and a transistor Q1 as the second switching device in which collector is connected with anode of the diode D1 are provided.
In addition, a control unit 408, in which a control signal is output to the relay 406 and a control signal is output to the base of a transistor Q1 through a resistance R1, is provided.
Moreover, to the other end of relay 406, direct current high voltage (DC280V) from a power unit 410 for the inverter for the inverter circuit where the compressor of the air conditioning machine is driven is applied. In addition, to the emitter of transistor Q1, direct current low voltage (DC16V) from a power unit 412 for the control of the inverter circuit of the air conditioning machine is applied.
As a result, the relay 406 as the first switching device and the transistor Q1 as the second switching device are switched.
Consequently, direct current high voltage (DC280V) is supplied from the power unit 410 for the inverter to drive the compressor of the air conditioning machine. Moreover, direct current low voltage (DC 16V) is supplied from the power unit 412 for the control of the air conditioning machine. Therefore, the solenoid valve mechanical power source need not be separately prepared, and the cost can be reduced.
However, as for this construction, the power unit 410 for the inverter to drive the compressor of the air conditioning machine and the power unit 412 for the control of the air conditioning machine are necessary. Therefore, it can be insistently used for only the air conditioning machine, and it is not possible to use it for other usages generally.
After the plunger is attracted in the direction of the attracting member, a minimum holding current should keep being applied to the electromagnetic coil. As a result, useless power is consumed.
Therefore, the instant applicant, in Patent Document 3 (JP, 2014-105722, A), the solenoid valve drive control device is proposed. That is, in this solenoid valve driving control device, in an open valve drive period (A) for opening a valve port formed to the valve seat, after applying direct current high voltage (Va) to the solenoid, it is composed that a direct current low voltage (Vb) is applied for holding period (B) to hold the state of an open valve. Furthermore, when the supply voltage to the solenoid is switched from the open valve drive period (A) to the holding period (B), the voltage is decreased from direct current high voltage (Va) toward direct current low voltage (Vb) in the constant gradient. In such a way, the solenoid valve drive control device in which the voltage reduction device is provided is proposed.
As a result, the winding wire of the solenoid (electromagnetic coil) need not be extra rolled. Therefore, the member and number of processing are decreased, so that the cost can be reduced.
Moreover, after the plunger is attracted in the direction of the attracting member, a minimum holding current should keep being applied to the electromagnetic coil. However, the electric current is extremely low, and useless power never be consumed. Moreover, the phenomenon, in which the plunger is disengaged, is not be generated.
By the way, as for such a solenoid valve, the coiled body case is enlarged. Therefore, power that is required for attracting the plunger is also increased. In addition, when the coiled body case is large, the stray capacity of the coil is increased. As a result, big inrush current flows to the stray capacity at the superimposed voltage to the coil.
Moreover, when the inrush current is generated, the noise that originates in inrush current is occurred. It might not be able to meet EMC standard (Electromagnetic Compatibility) concerning the EMI measurement of a general standard among related standards.)